Development and Validation of a Motion and Loading System for a Rat Knee Joint In Vivo

Abstract

The influence of biomechanical stimuli on modulating cartilage homeostasis is well recognized. However, many aspects of cellular mechanotransduction in cartilage remain unknown. We developed a computer-controlled joint motion and loading system (JMLS) to study the biological response of cartilage under well-characterized mechanical loading environments. The JMLS was capable of controlling i) angular displacement, ii) motion frequency, iii) magnitude of the axial compressive load applied to the moving joint, and it featured real-time monitoring. The accuracy and repeatability of angular position measurements, the kinematic misalignment error as well as the repositioning error of the JMLS were evaluated. The effectiveness of the JMLS in implementing well-defined loading protocols such as moderate Passive Motion Loading (PML) and increased Compressive Motion Loading (CML) were tested. The JMLS demonstrated remarkable accuracy and reliability for the measurement and kinematics tests. Moreover, the effectiveness test demonstrated the ability of the JMLS to produce an effective stimulus via PML that led to the suppression of the catabolic effects of immobilization. Interestingly, the biological response of the CML group was catabolic and exhibited a pattern similar to that observed in the immobilization group. This novel system may be useful for joint biomechanics studies that require different treatment conditions of load and motion in vivo.

Knee loading stimulates healing of mouse bone wounds in a femur neck

“…There are other forms of mechanical loading such as joint rotation [26, 27], and whole-body and local vibrations [28, 29]. To our knowledge, however, no loading modality has been clinically applied for treatment of a femur neck or head.…”

Matrix metalloproteinase-3 in articular cartilage is upregulated by joint immobilization and suppressed by passive joint motion

“…During the middle of each immobilization period (for 6 and 24 hour groups), and daily, 12 hours after the initial application of the casts (for 7 day group), rats were anesthetized, the casts were removed, and the rats were placed on a joint loading system (Gu, et al 2009) for 1 hour. During that period, these rats were subjected to motion loading at a frequency of two cycles per minute, with a range of motion between 65° and 115°, while a separate group of rats were maintained in the device without motion, at 115° of knee flexion (sham group).…”

Effects of immobilization and remobilization on the ankle joint in Wistar rats

“…Gu et al (18) have shown that physical exercise can reduce pain, maintain a range of motion, and thus reduce the time of hospitalization or rehabilitation. Among physical exercises, those that are performed in water, which has the added benefits of the physical properties of water such as heat and pressure, can contribute to pain relief and the reduction of edema and can facilitate ease of movement (19).…”